1. Field of the Invention
The present invention relates broadly to hand-held electronic GPS-based navigation aids and related methods for facilitating navigation. More particularly, the present invention concerns a GPS device and method for converting display information between a first display mode and a second display mode by negativizing pixels or other image elements, wherein negativizing entails converting lighter image elements to darker image elements and converting darker image elements to lighter image elements so as to result in reduced total emission of light.
2. Description of the Prior Art
Outdoor enthusiasts, sportsmen, law enforcement personnel, military personnel, and many others increasingly use hand-held electronic global positioning system (GPS) devices to navigate while afield. Commonly-available GPS devices typically include at least a processor, a receiver, and an antenna for receiving position signals from a plurality of known locations (from, e.g., satellites in orbit) and, through a process of geometric triangulation, determining the relative location of the GPS device in terms of latitude, longitude, and even altitude. Many such devices allow users to display a variety of different types of maps, other images, navigation tools, and other information on a display component which is often a liquid crystal display (LCD) screen. The display component uses pixels or other image elements to communicate the information. When activated, these image elements allow light to pass through the screen, produce light, or otherwise result in an emission of light from the screen. The amount of emitted light can be substantial, and, in relatively dark ambient conditions, can be visible from a significant distance by people or animals. In the case of a hunter, for example, the emitted light could alert or drive away any wild game. Similarly, in the case of military personnel, the emitted light could alert an enemy of the user's location.
It is known in the prior art to allow users to manually control, at least to some extent, the color of one or more display elements. As such, it is possible for users to manually specify relatively dark display colors. Unfortunately, manually specifying different colors requires a significant amount of time and effort to navigate menus and make selections, which cannot be done quickly or easily at any time, particularly not in the field under low light or other difficult conditions.
Due to these and other disadvantages in the prior art, a need exists for a GPS device capable of displaying information while minimizing emitted light.